In order to simply remove burnt-on food stains on cooking device that requires heating of plates and oven dishes for grilled meat and the like, cooking device has previously been proposed, for example, that forms a thin film whose primary ingredient is zirconium oxide on the surface of the base material (see, e.g., Patent Document 4).
In addition, anti-stain products have previously been proposed which are configured by forming a thin film containing silicon dioxide, zirconium oxide, and phosphoric acid on the surface of a base material of the product, and incorporating lithium ions in this thin film in a dispersed state (see, e.g., Patent Documents 1-3). It is held that such anti-stain products inhibit staining, and that stains are easily removable even once staining has occurred.
As a method of manufacture of anti-stain products that are provided with such properties, a method has been proposed wherein a lithium compound is brought into contact under heating with a thin film containing silicon dioxide and zirconium oxide that has been formed on a base material of the product, and lithium ions are diffused from the surface toward the interior of the aforementioned thin film, whereby lithium ions are incorporated into the thin film in a dispersed state.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2002-019007
Patent Document 2: Japanese Unexamined Patent Application, First Publication No. 2005-170057
Patent Document 3: Japanese Unexamined Patent Application, First Publication No. 2006-015754
Patent Document 4: Japanese Unexamined Patent Application, First Publication No. 2005-321108